Brake devices for elevators that bring the car to a stop in emergency situations or that hold it at the height of a stop, for example, during regular operation so that no unwanted movement of the car takes place are known in the prior art. Recently, such brake devices are in many cases no longer actuated in a purely mechanical fashion by an overspeed governor rope that exerts a locking action, but rather by means of actuators that are electrically, pneumatically, or hydraulically actuated. Such actuators cannot be embodied as arbitrarily powerful, particularly not if they must also be kept ready for operation even in the event of a power failure by means of an emergency power supply that travels along with the car. It is therefore already known to have such actuators not act directly on the brake linings, for example like a brake piston that is known from passenger vehicles, but rather to act on it via a lever transmission that intensifies the force exerted by the actuators.
One example of this is European patent application EP 1 067 084 A1. The patent application proposes an actuator, which is embodied in the form of a solenoid, hydraulic cylinder, or lifting spindle motor and via a tie rod, acts on a toggle lever mechanism that increases the actuation forces by several times and in this way, the brake shoes are acted on with corresponding normal forces.
In this design, a critical feature is that the toggle lever mechanism has pivot points that are supported in stationary fashion relative to the car. In this way, the position of the toggle lever mechanism is necessarily predetermined by the position that the car currently assumes relative to the guide rail at the point at which the toggle lever mechanism is to press the brake linings against the guide rail. This means that an automatic centering of the toggle lever mechanism relative to the guide rail used for the braking is not possible. Instead, the toggle lever mechanism is only centered on the guide rail if the entire car is held in its car guides on the guide rails so that the guide rail used for the braking has a precisely centered position at the height of the toggle lever mechanism.
The object of the invention is to remedy this problem.